Electric drive motor

ABSTRACT

An electric drive motor with a rotor in the form of an external rotor and with a stator, which has a base body comprised of heat conductive material. A bearing hub for the rotor and a support that extends radially away from the hub and is for containing a printed circuit board. The printed circuit board is equipped with electronics and is disposed on a side of the support oriented away from the rotor for the sake of an improved removal of the dissipated heat that is produced in the electronics, a multitude of concentric cooling ribs are embodied on the radial surface of the support oriented toward the rotor.

PRIOR ART

The invention relates to an electric drive motor.

In a known, electronically commutated electric drive motor of this kind(DE 41 22 529 A1), an annular wall is attached to and of one piece withthe outer annular edge of the support and this wall encloses thecup-shaped rotor with a radial gap spacing and has axial cooling ribs onits outside oriented away from the rotor. Switching transistors that arepresent in the power electronics and are for the electronic commutationare disposed on the printed circuit board so that their cooling surfaceslie flat against the radial surface of the support and are pressedagainst it by means of leaf springs. The dissipated heat that isessentially produced by the power transistors travels by way of theflange-like support into the annular wall and is dissipated relativelywell here into the surrounding air since the rotor turning inside theannular wall also provides for a rapid exchange of the air disposedthere.

ADVANTAGES OF THE INVENTION

The drive motor according to the invention has the advantage that bymeans of the concentric cooling ribs, not only is the surface area ofthe base body that acts as a cooling surface increased, but also anideal circulation around the cooling ribs is produced in particular byvirtue of the air flow against them, which is produced by the rotor thatis embodied in the form of an external rotor so that on the whole, theremoval of dissipated heat from the electronics is accelerated andimproved. The heat dissipation capacity can be still further increasedsuccessively if, in accordance with preferred embodiments of theinvention, large openings are let into the support. The openings canalso interrupt the concentric cooling rings, and the printed circuitboard is covered by a covering cap fastened to the support and the capbottom of this covering cap is provided with openings that continue onin hollow cylindrical pins that extend to the support and are alignedwith the openings in the support. In addition, the rotor has airopenings in its cup bottom disposed opposite from the radial surface ofthe support with axial spacing. As a result, a good air exchange isassured on the inside of the motor, which improves the air removal fromthe inside of the motor and thus increases the cooling capacity.

If, according to another embodiment of the invention, the hollow chamberbetween the covering cap and the radial surface of the support orientedtoward it is lined with a favorably heat conducting molded mass, thenadditional energy paths are produced. The energy paths conveydissipation heat from the electronics by way of the molded mass on theone hand to the cap and on the other hand to the base body and fromthere, dissipate the heat to the surrounding air.

Another improvement of the heat dissipation can be achieved by way of anadditional energy path which, as is the case with the known drive motordescribed at the beginning, leads from the electronics by way of thesupport to an encompassing cylinder that is attached to this support onthe edge and is of one piece with it axially, which also has additionalaxial cooling ribs on the outside. The rotor turning inside theencompassing cylinder also provides for an intensive air exchangeagainst the inner wall of the encompassing cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail in conjunction with anexemplary embodiment shown in the drawings.

FIG. 1 is a longitudinal section through an electric drive motor,

FIG. 2 is a view of a base body of the stator of the drive motor, with amounted printed circuit board, in the direction of the arrow II in FIG.1.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

In a known manner, the motor with electronic commutation that isdepicted in FIG. 1 as an exemplary embodiment for an electric drivemotor has a rotor 11, which is embodied here in the form of an externalrotor, and a stator 12, which has a base body 13 comprised of favorablyheat conductive material, e.g. aluminum or magnesium. A bearing hub 31,a flange-like support 132 that extends away from the hub, and anencompassing cylinder 133 attached axially to the outer circular edge ofthe support 132 are embodied as being of one piece inside the base body13. On the outside of its bearing hub 131, the base body 13 supports abundle of laminations 14, in which a stator or armature winding 15 isreceived. The power supply to the stator winding 15 is carried out byway of connection lugs 16.

The rotor 11, which is embodied as cup-shaped, is supported in aradially fixed manner on a rotor shaft 17, which is received so that itcan rotate in the bearing hub 131 by means of two bearings andencompasses the stator winding 15 with its cylindrical cup part. Theexciter poles are disposed in a known manner in the form of permanentmagnet segments 18 on the inner wall of the cylindrical cup part.

The power electronics required for the electronic commutation areaccommodated on a printed circuit board 19, which is disposed on theside of the support 132 of the base body 13 oriented away from the rotor11. The electronics include a number of switching transistors 20 thatare embodied as power transistors, which are disposed on the printedcircuit board so that with their cooling surfaces 21, they lie flatagainst the radial surface of the support 132 oriented toward theprinted circuit board 19. By means of spring brackets 36 that areembodied as leaf springs, which are fastened in the support 132 of thebase body 13 and rest with frictional, non-positive adhesion against theback side of the printed circuit board 19 oriented away from thetransistors 20, the printed circuit board 19 is attached to the support132 so that the cooling surfaces 21 of the switching transistors 20 arepressed against the support 132. The connection lugs 16 for the statorwinding 15 are likewise affixed to the printed circuit board 19. Thepower supply is provided for by an attachment plug 22 which is connectedwith its plug housing 221 to the base body 13 and is guided with itsplug contacts 222 against the printed circuit board 19.

The printed circuit board 19 with the electronics is covered over by acovering cap 23 that is fastened to the support 132. The plug housing221 thereby protrudes through a radial bore 25 into the encompassingcylinder 133 and is placed with a groove 24 onto the edge of thecylindrical part of the covering cap 23. The hollow chamber between thecovering cap 23 and the support 132 is lined with a favorably heatconductive molded mass 26, wherein the printed circuit board 19 and theswitching transistors 20, with the exception of the cooling surfaces 21that are pressed against the support 132, are enclosed on all sides bythe molded mass 26. A number of heat conduction paths are provided for arapid and effective removal of the dissipation heat produced by theswitching transistors 20. To this end, on the one hand, a multitude ofconcentric cooling ribs 27 are embodied on the radial surface of thesupport 132 oriented toward the rotor 11 and these concentric coolingribs 27 are interrupted in their annular course by extensive openings 28(FIG. 2) that are let into the support 132 (FIG. 2). The air flowproduced by the rotor 11, which turns with a gap spacing in theencompassing cylinder 133, flows around these annular cooling ribs 27 inan ideal manner so that a large part of the dissipated heat of theswitching transistors 20 is dissipated by way of the support 132 and thecooling ribs 27. Another energy path travels by way of the support 132into the encompassing cylinder 133, which has axial ribs 29 on itsoutside oriented away from the rotor 11, which favorably dissipate theheat from the encompassing cylinder 133 to the environment. In addition,there is a third heat conducting path from the switching transistors 20by way of the molded mass 26 to the covering cap 23, which in turnradiates the dissipated heat to the environment.

In order to improve the air exchange on the inside of the motor and inorder thereby to more rapidly remove the air being heated against thecooling ribs 27 to the outside, on the one hand, air openings 30 areprovided in the cup bottom of the cup-shaped rotor 11 and on the otherhand, openings 31 are let into the cap bottom of the covering cap 23,which continue on in hollow pins 32 that are of one piece with thecovering cap 23, which in turn extend to the openings 28 in the support132 and are aligned with the openings 28. By means of the openings 31and the openings 28 in the support 132, as well as the air openings 30in the rotor 11, a very favorable air exchange is assured on the insideof the motor, so that on the whole, the favorably heat conductive basebody 13 that is made of magnesium or aluminum can very rapidly give offthe dissipated heat, which has been transmitted by all of the powertransistors 20, to the continuously exchanged air.

An additional opening 33 is also provided in the center of the coveringcap 23, which likewise continues on into a hollow pin, which extends tothe bearing hub 131 or to the bearing of the rotor shaft 17, whichbearing is embodied in the form of a dome bearing 35. The pin axis isthen aligned with the axis of the rotor shaft 17. An extension of thedrive motor to a second drive is possible by means of this additionalopening 33 for the end of the rotor shaft 17.

The foregoing relates to preferred exemplary embodiments of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. An electric drive motor comprising a rotor (11)in the form of an external rotor, a stator (12), said stator has a basebody (13) comprised of heat conductive material, a bearing hub (131) forthe rotor (11) and a support (132) that extends radially away from saidhub and is for supporting a printed circuit board (19), said printedcircuit board is equipped with electronics and is disposed on a side ofthe support (132) oriented away from the rotor (11) in an axialdirection, a multitude of concentric cooling ribs (27) are embodied onthe radial surface of the support (132) oriented toward the rotor (11)in an axial direction, the printed circuit board (19) is covered over bya covering cap (23), said covering cap is fastened to the support (132),and a hollow space remaining between the covering cap (23) and thesupport (132) is lined with a favorably heat conductive molded material(26); and openings (31) are provided in a bottom of the covering cap(23), which continue on in hollow pins (32) that extend to the support(132) and are aligned with openings (28) in the support (132).
 2. Themotor according to claim 1, in which openings (28) are let into thesupport (132) and extend over the concentric cooling ribs (27) anddivide the cooling ribs into separate arc sections.
 3. The motoraccording to claim 2, in which the printed circuit board (19) is coveredover by a covering cap (23), said covering cap is fastened to thesupport (132), and a hollow space remaining between the covering cap(23) and the support (132) is lined with a favorably heat conductivemolded material (26).
 4. The motor according to claim 2, in which therotor (11) is embodied as cupshaped and has air openings (30) in a cupbottom disposed opposite and spaced axially apart from the radialsurface of the support (132).
 5. The motor according to claim 2, inwhich the base body (13) has an encompassing cylinder (133), which isplaced axially encompasses the rotor (11) with a radial gap spacing, andthat axial ribs (29) which protrude from the encompassing cylinder (133)are provided on an outside oriented away from the rotor (11).
 6. Themotor according to claim 2, in which the base body (13), which isembodied as being of one piece with the bearing hub (131), is made ofaluminum or magnesium.
 7. The motor according to claim 1, in which therotor (11) is embodied as cupshaped and has air openings (30) in abottom of the cupshaped rotor disposed opposite and spaced axially apartfrom the radial surface of the support (132).
 8. The motor according toclaim 1, in which the base body (13) has an encompassing cylinder (133),which is placed axially encompasses the rotor (11) with a radial gapspacing, and that axial ribs (29) which protrude from the encompassingcylinder (133) are provided on an outside oriented away from the rotor(11).
 9. The motor according to claim 1, in which the base body (13),which is embodied as being of one piece with the bearing hub (131), ismade of aluminum or magnesium.
 10. The motor according to claim 1, inwhich the rotor (11) is embodied as cupshaped and has air openings (30)in a bottom disposed opposite of the cupshaped rotor and spaced axiallyapart from the radial surface of the support (132).
 11. The motoraccording to claim 1, in which the rotor (11) is embodied as cupshapedand has air openings (30) in a cup bottom disposed opposite and spacedaxially apart from the radial surface of the support (132).
 12. Themotor according to claim 1, in which the base body (13) has anencompassing cylinder (133), which is placed axially encompasses therotor (11) with a radial gap spacing, and that axial ribs (29) whichprotrude from the encompassing cylinder (133) are provided on an outsideoriented away from the rotor (11).
 13. An electric drive motorcomprising a rotor (11) in the form of an external rotor, a stator (12),said stator has a base body (13) comprised of heat conductive material,a bearing hub (131) for the rotor (11) and a support (132) that extendsradially away from said hub and is for supporting a printed circuitboard (19), said printed circuit board is equipped with electronics andis disposed on a side of the support (132) oriented away from the rotor(11) in an axial direction, a multitude of concentric cooling ribs (27)are embodied on a radial surface of the support (132) and orientedtoward the rotor (11) in the axial direction, and the electronicsinclude switching transistors (20) with cooling surfaces (21) that aresecured to the printed circuit board (19) so that the cooling surface(21) lies flat against the radial surface of the support (132) orientedtoward the printed circuit board (19).
 14. The motor according to claim13, in which the printed circuit board (19) is covered over by acovering cap (23), said covering cap is fastened to the support (132),and a hollow space remaining between the covering cap (23) and thesupport (132) is lined with a favorably heat conductive molded material(26).
 15. The motor according to claim 14, in which openings (31) areprovided in the cap bottom of the covering cap (23), which continue onin hollow pins (32) that extend to the support (132) and are alignedwith the openings (28) in the support (132).
 16. The motor according toclaim 13, in which the cooling surfaces (21) are pressed against theradial surface by means of spring brackets (36) and that the springbrackets (36) are fastened in the support (132) and pressed against aside of the printed circuit board (19) oriented away from the switchingtransistors (20).
 17. An electric drive motor comprising a rotor (11) inthe form of an external rotor, a stator (12), said stator has a basebody (13) comprised of heat conductive material, a bearing hub (131) forthe rotor (11) and a support (132) that extends radially away from saidhub and is for supporting a printed circuit board (19), said printedcircuit board is equipped with electronics and is disposed on a side ofthe support (132) oriented away from the rotor (11) in an axialdirection, a multitude of concentric cooling ribs (27) are embodied on aradial surface of the support (132) and oriented toward the rotor (11)in an axial direction, openings (28) are let into the support (132) andextend over the concentric cooling ribs (27) and divide the cooling ribsinto separate arc sections, and the electronics include switchingtransistors (20) with cooling surfaces (21) that are secured to theprinted circuit board (19) so that the cooling surface (21) lies flatagainst the radial surface of the support (132) oriented toward theprinted circuit board (19).
 18. An electric drive motor comprising arotor (11) in the form of an external rotor, a stator (12), said statorhas a base body (13) comprised of heat conductive material, a bearinghub (131) for the rotor (11) and a support (132) that extends radiallyaway from said hub and is for supporting a printed circuit board (19),said printed circuit board is equipped with electronics and is disposedon a side of the support (132) oriented away from the rotor (11) in anaxial direction, a multitude of concentric cooling ribs (27) areembodied on a radial surface of the support (132) and oriented towardthe rotor (11) in the axial direction, the printed circuit board (19) iscovered over by a covering cap (23), said covering cap is fastened tothe support (132), and a hollow space remaining between the covering cap(23) and the support (132) is lined with a favorably heat conductivemolded material (26), and eth electronics include switching transistors(20) with cooling surfaces (21) that are secured to the printed circuitboard (19) so that the cooling surface (21) lies flat against the radialsurface of the support (132) oriented toward the printed circuit board(19).
 19. An electric motor comprising a rotor (11) in the form of anexternal rotor, a stator (12), said stator has a base body (13)comprised of heat conductive material, a bearing hub (131) for the rotor(11) and a support (132) that extends radially away from said hub and isfor supporting a printing circuit board (19), said printed circuit boardis equipped with electronics and is disposed on a side of the support(132) oriented away from the rotor (11) in an axial direction, amultitude of concentric cooling ribs (27) are embodied on a radialsurface of the support (132) and oriented toward the rotor (11) in theaxial direction, openings (28) are let into the support (132) and extendover the concentric cooling ribs (27) and divide the cooling ribs intoseparate arc sections, and the cooling surfaces (21) are pressed againstthe radial surface by means of spring brackets (36) and that the springbrackets (36) are fastened in the support (132) and pressed against aside of the printed circuit board (19) oriented away from the switchingtransistors (20).
 20. An electric drive motor comprising a rotor (11) inthe form of an external rotor, a stator has a base body (13) comprisedof hear conductive material, a bearing hub (131) for the rotor (11) anda support (132) that extends radially away from said hub and is forsupporting a printed circuit board (19), said printed circuit board isequipped with electronics and is disposed on a side of the support (132)oriented away from the rotor (11) in an axial direction, a multitude ofconcentric cooling ribs (27) are embodied on a radial surface of thesupport (132) and oriented toward the rotor (11) in the axial direction,the printed circuit board (19) is covered over by a covering cap (23),said covering cap is fastened to the support (132), and a hollow spaceremaining between the covering cap (23) and the support (132) is linedwith a favorably heat conductive molded material (26), and the coolingsurfaces (21) are pressed against the radial surface by means of springbrackets (36) and that the spring brackets (36) are fastened in thesupport (132) and pressed against a side of the printed circuit board(19) oriented away from the switching transistors (20).